1. Field of the Invention
The invention relates to exercise equipment. More particularly, the invention relates to a portable foot operated exercise device.
2. Brief Description of the Prior Art
The concept of a portable foot operated exercise device is old in the art. As early as 1940, R. L. Titus described such an “exerciser” in U.S. Pat. No. 2,256,001. The Titus device includes a top disk and a bottom disk which are rotatable relative to each other. The user steps onto the top disk and causes it to rotate by moving his/her legs and or torso. A similar, though slightly more sophisticated device was described by Honer in U.S. Pat. No. 3,512,774 in 1970. A similar, though even more sophisticated device was described in 1987 by Smith in U.S. Pat. No. 4,687,198. The Titus concept was carried further by McKechnie et al. in U.S. Pat. No. 6,413,197 (2002) which describes a device having upper and lower members coupled to each other by a centrally located torsion spring. The user stands on the upper member and causes it to swivel relative to the lower member. Unlike Titus and those who followed, the upper and lower members are not circular and the centrally located torsion spring provides potentially more resistance than the earlier devices.
In 1958, H. L. Stewart described a completely different portable foot operated exercise device in U.S. Pat. No. 2,950,120. Stewart's “locomotion device” is a simple curved board which is placed convex side down on the floor. The user steps onto the board with feet spread apart. By rocking back and forth and swiveling, the board can be made to travel across the floor, unlike the Titus style devices which remain stationary. In the 1960s, Sundquist and Modlar carried the Stewart concept further with more complex devices as described in U.S. Pat. Nos. 3,108,802 and 3,438,626, respectively. Still, in 1981, Heatwole described a device similar to those of Sundquist and Modlar which requires that the user cause opposite sides of the device to be lifted off the floor in order to zig-zag the device forward across the floor. See, U.S. Pat. No. 4,285,516. In 1996, Liang described a device similar to that of Heatwole in U.S. Pat. No. 5,547,447. In 1998, Bruntmyer described a “tilt walker sport board” in U.S. Pat. No. 5,795,277 which is similar in concept to Liang and the predecessors but which has a spring biased suspension and a centrally located rope which the user can grasp to aid in balance.
In 1971, Quong Y. Chang described a “rockable exercise platform for skiers” which is a bowl shaped device with a tread pad on top and an adjustable weight inside. The user stands on the tread pad and, by tilting and swiveling, can simulate forces encountered during skiing.
While all of the above-described devices are relatively simple in construction as compared to many of the more complex modern exercise devices, there is a need for a much simpler exercise device. Moreover, while all of the above-described devices are portable as compared to the relatively immovable exercise devices like large treadmills and elliptical walkers, etc., they are either too heavy, too bulky or both to be carried while traveling. In addition, the above-described devices may not function properly on a carpeted floor or on a highly polished floor.